The pneumatic tire has been the solution of choice for vehicular mobility for over a century. Modern belted, radial carcass, pneumatic tires are remarkable products that provide an effective means for supporting applied loads while allowing reasonable vertical and lateral compliance. The pneumatic tire obtains its mechanical attributes largely due to the action of internal air pressure in the tire cavity. Reaction to the inflation pressure corrects rigidities to the belt and carcass components. Inflation pressure is then one of the most important design parameters for a pneumatic tire.
Good pressure maintenance is required to obtain the best performance from a pneumatic tire. Inflation pressure below that specified can result in a loss of fuel economy. Of primary importance is that a conventional pneumatic tire is capable of very limited use after a complete loss of inflation pressure. Many tire constructions have been proposed for continued mobility of a vehicle after a complete loss of air pressure from the tire. Commercially available runflat tire solutions are pneumatic tires having added sidewall reinforcements or fillers to permit the sidewalls to act in compression as load supporting members during deflated operation. This added reinforcement often results in the disadvantages of higher tire mass and reduced riding comfort. Other attempts to provide runflat capability utilize essentially annular reinforcing bands in the tire crown portion. In these solutions, the rigidity of the tread portion results partly from the inherent properties of the annular reinforcing band and partly from the reaction to inflation pressure. Still other solutions rely on secondary internal support structures attached to the wheel. These supports add mass to the mounted assembly and either increase mounting difficulty or may require the use of multiple piece rims. All of these approaches are hybrids of an otherwise pneumatic tire structure and suffer from design compromises that are optimal for neither the inflated nor deflated states. In addition, these runflat solutions require the use of some means to monitor tire inflation pressure and to inform the vehicle operator if the inflation pressure is outside the recommended limits.
A tire designed to operate without inflation pressure may eliminate many of the problems and compromises associated with a pneumatic tire. Neither pressure maintenance nor pressure monitoring is required. Structurally supported tires such as solid tires or other elastomeric structures to date have not provided the levels of performance required from a conventional pneumatic tire. A structurally supported tire solution that delivers pneumatic tire-like performance would be a desirous improvement.